The bridge pose is a gentle inversion that helps strengthen the muscles of the back, improves flexibility in the spine and brings blood flow to the thyroid glad at the base of the throat.  It can be done as a traditional asana, by holding the pose for some (comfortable ) time.  It it’s not comfortable to hold the pose, we suggest a rolling bridge, which is more like a vinyasa or flow type of practice that coordinates the breath with the movement.  I really enjoyed reading an article from Leslie Kamanoff at   http://yogaanatomy.net/dwipada-pitham/
I enjoyed his description of breathing in reverse to the obvious way we would breathe in this pose–inhale as the buttocks lift, and exhale as you lower back to the floor.  Check it out!

The Bridge Pose